Treating glass articles



Patented May 26', 1931 UNITED STATES ROWLAND D. OF COBNING, NEW YORK,ASSIGNOR TO CORNING GLASS WORKS,

PATENT OFFICE OI CORNING, NEW YORK, A COBIPORATIONWF NEW YORK TREATINGGLASS AlRTICLES No Drawing. Application filed March 5, 1929, Serial No.344,592. Renewed April 6,1931.

. This invention relates to treating glass articles and mdreparticularly to preventing of loss of strength; of inside frostedarticles vsuchas lamp bulbs. l

It is well known that the surface of certain glasses which has beenfrosted is subject to weathering which causes a mechanical weakeningwhen the article is subjected to -rapid heating.

It is a matter of common knowledge that when lamp bulbs prior to beingfabricated into lamps are stored for indefinite PBI'lOdSJSO that boththeir inner and outer surfaces are exposed to weathering and they aresubjected to the rapid heating, incident to lamp manufacture, theybecome mechanically tain salts naturally present inthe washwaterweakened. This condition becomes serious when inside frosted bulbsare usedas a slight external blow on the bulb is very likely to cause itto break.

The object of the present invention is to prevent mechanical weakeningof glass articles which is caused by"weathering.

I have discovered that by using certain salts in the water in which thebulbs are washed after frosting that different results may be -Obtal h6(l; for instance, calcium or lime salts are verytdetrimental to thestrength of the articles whereas aluminum salts in the wash water havebeen found to maintain the strength of the articles. Moreover, I havediscovered that the injurious effects of cermay be completely overcomebythe addition of other salts, and 'I not only am able to neutralize theundesirable effects of the natural salt,-but can so control thecomposition as to produce a beneficial effect.

My invention embodies the introduction into the wash water in whichglass articles are to be washed of a suflicient quantity of aluminumsalts to cause the articles to retain their strength so that they may bestored for indefinite periods without serious weakenin when they aresubsequently subjected to rapi heating.

In carrying my invention into practice, I

introduce into the wash water; for instance,

one which contains in terms of oxides ten ('10) parts per million oflime, two (2) parts per m illion.of magnesia, and six (6) parts permillion of sulphuric anhydride; one hundred (100) parts per million ofaluminum fluoride. By'doing this I not only overcome the detrimentalefiects of the lime and magnesium salts initially present in the washwater, but eliminate the ill effects of weatheringssuth as abovedescribed.

ile from the foregoing it may seem that I am merely offsetting thedetrimental effects of the lime and magnesium salts,,I havefound thatpure distilled water to which no alu-- minum fluoride has been addedwill not produce as good results as the water above referred to, treatedas set forth. y

On the other hand, I still further can improve the resistance of glassarticles to such mechanical weakening by using pure distilled water towhich there has been added about minum fluoride.

While in the above -;;I refer to aluminum,

fluoride, I havev found that aulininum sulphate will, under the properconditions and circumstances, serve equally well as thefluoride. Itherefore do not wish to have my invention restricted to the use of thefluoride but wish to have the term fluoridefas used herein, interpretedto include the sulphate as well; nor do I'wish to be limited as to thequantities of the aluminum salts set forth in the foregoing. examplesasthese quantitiesadded to the water may be varied up to seven hundredfifty (750) parts per milli n in. accordance with thechemical'conipositionof the water used.

' I claim:

1. The method of treating glass articleswhich includes washing them inwater 0on tainin simple aluminum fluoride.

' 2. T e method of treating glass articl s which includes washing themin water containing not more than seven hundred fifty parts 'per millionof simple aluminum {ROWLAND 1). SMITH.

